Page 24 - Free State Summer 2022

TOTAL PLANT MANAGEMENT (Continued)

have fewer plant damaging residues over the past 30 A helpful scouting method is to use
years. The horticultural oils work best when applied to
low- to medium-sized populations of scale. With larger the 3-M brand blue painter's tape
populations, especially armored scales, the covers cluster, or black electrician’s tape. Wrap
making contact with the oil difficult.

Research it around a branch sticky side out,
We received a grant from the Maryland Nursery, smooth side toward the branch,
Landscape, and Greenhouse Association for 2014 to 2016. and monitor for crawlers as they
Our goal was to identify major scale insects present in
area nurseries and landscapes and develop a monitoring move onto the tape and get stuck.
program to detect and alert growers and arborists to
the crawler period, the most susceptible stage for scale
control. We hired students and technicians to scout and A helpful scouting method is to use the 3-M brand
sample plant material, monitoring the different scales and blue painter's tape or black electrician’s tape. Wrap it
their life stages, and correlating that with the degree-day around a branch sticky side out, smooth side toward
information and plant phenology. From this information the branch, and monitor for crawlers as they move
we developed IPM (integrated pest management) Alerts onto the tape and get stuck. This will provide you with
and Scale Fact Sheets. Industry professionals can visit more timely local information for your crawlers. Another
our website at https://Extension.umd.edu/ipm. Go to the method of estimating the crawler stage is based on plant
fact sheet section and you can download a PDF of each phenology, a correlation with the time particular plants
fact sheet we have written on specific scale species. Each
Friday we publish a weekly IPM Alert that lets growers know
which insects and diseases are active and when specific
scale species are in the crawler susceptible stage. This is
published on this website each week.

Insects respond to temperature, not the calendar. Using
degree-days instead of actual dates takes into account
yearly temperature fluctuations and prevents you from
missing the crawler stage. The weekly IPM Alert reports
also contain information on degree-days accumulated
in the different areas of Maryland, western versus Eastern
Shore or the southern section. Degree-days are obtained
using a base of 50 F. Insect development is controlled by
temperature and we use degree day accumulation to
predict when crawler stages of the various scale insects
will occur. Our project then correlated the appearance of
crawlers to degree-days accumulated. We did this over
a couple of years to account for year-to-year variations.
This provides better information to industry professionals
for timing sprays. For example, for a specific scale insect
species when you get up around a certain number
of degree-days, say it is 402 degree-days for that first
generation, when you are getting to around 350 or 400
start looking at your customers’ plants for presence of Fine Earth Landscaping. Japanese maple scale on 30-year-old wisteria
crawlers. planting
Photo: Bernie Mihm

24 SUMMER 2022 • Free State News